遗传算法
Posted 故园的梨花
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///Users/apple/Documents/ga/ga.xcodeproj // main.c // ga // // Created by APPLE on 16/3/31. // Copyright © 2016年 ETaoBook. All rights reserved. // #include <stdio.h> #include <stdlib.h> #include <time.h> #define POPSIZE 500 #define MAXIMIZATION 1 #define MINIMIZATION 2 #define Cmax 100 #define Cmin 0 //x1 #define LENGTH1 10 //x2 #define LENGTH2 10 //一个染色体 #define CHROMLENGTH LENGTH1+LENGTH2 //功能模式 int FunctionMode=MAXIMIZATION; //群体大小 int PopSize=80; //终止代数 int MaxGeneration=1000; //交叉概率 double Pc=0.6; //变异概率 double pm=0.001; //个体 struct individual{ double value; double fitness;//适应度 char chrom[CHROMLENGTH]; }; int generation; int best_index; int worst_index; struct individual bestindividual; struct individual worstindividual; struct individual currentbest; struct individual population[POPSIZE]; void GenerateInitialPopulation(void);//生成初代群体 void GenerateNextPopulation(void);//生成下代群体 void EvaluatePopulation(void);//对个体进行评价 long DecodeChromosome(char *,int,int);//解码 void CalculateObjectValue(void);//计算函数值 void CalculateFitnessValue(void);//计算适应度 void FindBestAndWorstIndividual(void);//找到最好的个体在当前这一代 void PerformEvolution(void); void SelectionOperator(void);//选择运算 void CrossoverOperator(void);//交叉运算 void MutationOperator(void);//变异运算 void OutputTextReport(void); int main(void) { generation =0; GenerateInitialPopulation(); EvaluatePopulation(); while (generation<MaxGeneration) { generation++; GenerateNextPopulation(); EvaluatePopulation(); PerformEvolution(); OutputTextReport(); } return 0; } void GenerateInitialPopulation(void){ int i,j; srand((unsigned)time(NULL));//初始化随机数生成器 for (i=0; i<PopSize; i++) { for (j=0; j<CHROMLENGTH; j++) { population[i].chrom[j]=(rand()%10<5)?‘0‘:‘1‘; } population[i].chrom[CHROMLENGTH]=‘\0‘; } } void GenerateNextPopulation(void){ SelectionOperator(); CrossoverOperator(); MutationOperator(); } void EvaluatePopulation(void){ CalculateObjectValue();//计算函数值 CalculateFitnessValue();//计算适应度 FindBestAndWorstIndividual();//找出最佳个体 } long DecodeChromosome(char *string,int point,int length){//解码染色体,得出十进制数值。 int i; long decimal=0L; char *pointer; for (i=0, pointer=string+point;i<length;i++, pointer++) { decimal+=(*pointer-‘0‘)<<(length-1-i); } return decimal; } void CalculateObjectValue(void){//计算函数值 int i; long temp1,temp2; double x1,x2; for (i=0; i<PopSize; i++) { temp1=DecodeChromosome(population[i].chrom,0 , LENGTH1); temp2=DecodeChromosome(population[i].chrom, LENGTH1, LENGTH2); x1=4.096*temp1/1023.0-2.048; x2=4.096*temp2/1023.0-2.048; population[i].value=100*(x1*x1-x2)*(x1*x1-x2)+(1-x1)*(1-x1); } } void CalculateFitnessValue(void){//计算适应度 int i; double temp = 0.0; for (i=0; i<PopSize; i++) { if (FunctionMode==MAXIMIZATION) {//如果目标是求函数最大值的优化问题 if ((population[i].value+Cmin)>0.0) { temp=Cmin+population[i].value; }else{ temp=0.0; } }else if (FunctionMode==MINIMIZATION){//如果目标是求函数的最小值的优化问题 if (population[i].value<Cmax) { temp=Cmax-population[i].value; } else{ temp=0.0; } } population[i].fitness=temp; } } void FindBestAndWorstIndividual(void){ int i; double sum=0.0; bestindividual=population[0]; worstindividual=population[0]; for (i=1; i<PopSize; i++) { if (population[i].fitness>bestindividual.fitness) { bestindividual=population[i]; best_index=i; }else if (population[i].fitness<worstindividual.fitness){ worstindividual=population[i]; worst_index=i; } sum+=population[i].fitness; } if (generation==0) { currentbest=bestindividual; }else{ if (bestindividual.fitness<currentbest.fitness) { currentbest=bestindividual; } } } void PerformEvolution(void){ if (bestindividual.fitness<currentbest.fitness) { currentbest=population[best_index]; }else{ population[worst_index]=currentbest; } } void SelectionOperator(void){//选择运算 int i,index; double p,sum=0.0; double cfitness[POPSIZE]; struct individual newpopulation[POPSIZE]; for (i=0; i<PopSize; i++) { sum+=population[i].fitness; } for (i=0; i<PopSize; i++) { cfitness[i]=population[i].fitness/sum; } for (i=1; i<PopSize; i++) { cfitness[i]=cfitness[i-1]+cfitness[i]; } for (i=0; i<PopSize; i++) { p=rand()%1000/1000.0; index=0; while (p>cfitness[index]) { index++; } newpopulation[i]=population[index]; } for (i=0; i<PopSize; i++) { population[i]=newpopulation[i]; } } void CrossoverOperator(void){//交叉算子 int i,j; int index[POPSIZE]; int point,temp; double p; char ch; for (i=0; i<PopSize; i++) { index[i]=i; } for (i=0; i<PopSize; i++) { point=(rand()%PopSize)-i; temp=index[i]; index[i]=index[point+i]; index[point+i]=temp; } for (i=0; i<PopSize-1; i+=2) { p=rand()%1000/1000.0; if (p<Pc) { point=(rand()%CHROMLENGTH-i)+1; for (j=point; j<CHROMLENGTH; j++) { ch=population[index[i]].chrom[j]; population[index[i]].chrom[j]=population[index[i+1]].chrom[j]; population[index[i+1]].chrom[j]=ch; } } } } void MutationOperator(void){//变异 int i,j; double p; for (i=0; i<PopSize; i++) { for (j=0; j<CHROMLENGTH; j++) { p=rand()%1000/1000.0; if (p<pm) { population[i].chrom[j]=(population[i].chrom[j]==‘0‘)?‘1‘:‘0‘; } } } } void OutputTextReport(void){ int i; double sum; double average; sum=0.0; for (i=0; i<PopSize; i++) { sum+=population[i].value; } average=sum/PopSize; printf("gen=%d,avg=%f,best=%f,",generation,average,currentbest.value); for (i=0; i<CHROMLENGTH; i++) { printf("%c",currentbest.chrom[i]); } printf("\n"); }
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